K4CO4
K4CO4 is a semiconducting potassium-based oxide known for its structural complexity and metastable nature.

About K4CO4
K4CO4 is a complex potassium-based oxide that exhibits semiconducting electronic properties. As a compound characterized by a significant number of reported structural variations in materials databases, it represents a subject of ongoing interest for researchers exploring unconventional stoichiometry in alkali metal oxides. Its existence above the thermodynamic hull suggests that it is a metastable phase, requiring specific synthesis conditions to stabilize its structure. This complexity makes it a notable, if challenging, candidate for fundamental studies in solid-state chemistry. Given its electronic nature, it is primarily investigated for its potential role in specialized chemical environments where alkali-rich oxide frameworks are required. The material serves as a case study for understanding the stability limits of highly basic oxide systems.
Key Properties
Cross-validated computational properties for K4CO4, aggregated across 3 databases.
Band GapEnergy needed to move an electron from the valence band to the conduction band. Lower or zero values tend to behave more metallic; larger gaps are more insulating or semiconducting.
Energy Above HullThermodynamic distance from the most stable set of competing phases. 0 eV/atom is on the convex hull; small positive values may still be experimentally accessible.
StabilityA plain-language summary of the best reported energy-above-hull result. It reflects whether the lowest-energy structure is on, near, or far from the stability hull.
StructuresCount of reported calculated crystal structures for this formula, including alternate polymorphs, source databases, and observed space groups.
Reported Structures
Lowest-energy structures reported for K4CO4, ranked by energy above hull.
| Space GroupSymmetry classification of the crystal arrangement. The number is the international space-group index. | Crystal SystemBroad lattice family, such as cubic, tetragonal, monoclinic, or triclinic, derived from unit-cell symmetry. | Band Gap (eV)Electronic gap calculated for this specific reported structure, measured in electronvolts. | E above hull (eV/atom)Thermodynamic distance from the convex hull for this structure, normalized per atom. Lower is generally more stable. | E/atom (eV)Computed total energy normalized per atom. Use energy above hull, not this value alone, when comparing stability. | Density (g/cm³)Mass per relaxed crystal volume, reported in grams per cubic centimeter. |
|---|---|---|---|---|---|
| P42/n (No. 86) | tetragonal | 2.97 | 0.1609 | -5.384 | 2.67 |
| I-42m (No. 121) | tetragonal | 1.44 | 0.1828 | -5.363 | 2.01 |
| C2 (No. 5) | monoclinic | 2.03 | 0.1885 | -5.357 | 2.44 |
| Cm (No. 8) | monoclinic | 2.10 | 0.1910 | -5.354 | 2.44 |
| I-42m (No. 121) | tetragonal | 2.50 | 0.1945 | -5.351 | 2.52 |
| I-4 (No. 82) | tetragonal | 1.79 | 0.1948 | -5.351 | 2.51 |
| Cm (No. 8) | monoclinic | 1.60 | 0.2210 | -5.324 | 2.21 |
| Cm (No. 8) | monoclinic | 0.91 | 0.2609 | -5.284 | 2.05 |
| P-43m (No. 215) | cubic | 2.01 | 0.2825 | -5.263 | 2.43 |
| R3 (No. 146) | trigonal | 2.34 | 0.2839 | -5.261 | 2.45 |
| R3m (No. 160) | trigonal | 1.96 | 0.2847 | -5.261 | 2.39 |
| P1 (No. 1) | triclinic | 0.03 | 0.8630 | -4.682 | 1.67 |
Applications
Where K4CO4 is used.
Frequently Asked Questions
Common questions about K4CO4, answered from cross-validated data.
What is K4CO4?
K4CO4 is a semiconducting potassium-based oxide known for its structural complexity and metastable nature.
What is K4CO4 used for?
What is the band gap of K4CO4?
Is K4CO4 a metal, semiconductor, or insulator?
Is K4CO4 thermodynamically stable?
What is the crystal structure of K4CO4?
What is the density of K4CO4?
How many polymorphs of K4CO4 are known?
What elements does K4CO4 contain?
Where does the data for K4CO4 come from?
How It Compares
As a unique alkali-rich oxide, K4CO4 occupies a specialized niche in materials science. Unlike more common, thermodynamically stable ternary oxides, this compound exists in a metastable state, highlighting the intricate balance of ionic interactions within its lattice. It serves as a distinct example of how alkali metal-oxygen frameworks can be engineered, providing researchers with a reference point for exploring the limits of structural stability in non-standard oxide compositions.
Data sources & attribution
- materials_project — Data from the Materials Project. Cite: Jain et al., APL Materials 1, 011002 (2013).
- jarvis — Data from JARVIS (NIST). Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020).
- mpaloe — Data from mpaloe.
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